Servomex DF-130E, Operator'S Manual

Page: 60 / 88

56 DF-150
Troubleshooting
12.2.4 Temperature Effects on Sensor Performance
The output of the sensor, given a constant oxygen concentration, will vary
slightly with sensor temperature. Temperature effects are most pronounced at
concentrations near zero in the lower range analyzers. Percent range sensors
will exhibit almost no temperature sensitivity.
The effects of temperature are expressed in Table 10.
Range Temp Range
(70ºF nominal)
% of Reading/°F
(2% - 100% of range)
Typical Drift
(lower 2% of range)
0-50 ppm 45ºF – 95ºF ±0.32 ±65 ppb
0-100 ppm 45ºF – 95ºF ±0.32 ±125 ppb
0-500 ppm 45ºF – 95ºF ±0.32 ±250 ppb
0-1000 ppm 45ºF – 95ºF ±0.32 ±500 ppb
0-5000 ppm 45ºF – 95ºF ±0.24 ±2.5 ppm
0-10,000 ppm 45ºF – 95ºF ±0.20 ±5 ppm
0-5% 45ºF – 95ºF ±0.12 ±0.003%
0-10% 45ºF – 95ºF ±0.04 ±0.005%
0-25% 45ºF – 95ºF ±0.01 ±0.013%
Table 10: Typical Output Drift by Analyzer Range
12.2.5 Flow Rate Effects on Sensor Performance
Assuming a perfectly leak tight gas delivery system, flow rates above the
standard 1.0 scfh may increase the O2 readout by a few percent of reading.
Similarly, lower than standard flow rates may cause a decrease in the readout
by a few percent of reading.
At very low flow rates (< .2 scfh) O2 readings are much more sensitive to flow
rate changes. As a result, if the analyzer is recalibrated at lower than normal
flow rates, the new flow rate must be held /- 10%.
The normal insensitivity of Servomex sensors to flow rate changes is the basis
for the Flow Sensitivity Leak Check Method described in the section on Leaks
found on page 38.